Re: tube question
FWIW, tires and tubes were originally dusted with powdered mica, not talc! If you look at an old NOS tube you see a somewhat sparkly crystalline appearance to the dusting covering the tube. Talc does not look that way.
Original reason for mica: Completely resistant to water and humidity. It is hydrophobic, and stays dry and slippery despite moisture. Talc, on the other hand, turns gummy and loses its ability to permit the tube to 'slip', relieving stretch tension between the tube, rim, and inner casing of the tire.
Back in the late 40's my dad had boxes of the stuff (mica powder) labeled "B.F. Goodrich" at his service station and tire shop. Every time a used tube or tire was removed for service they were brushed with the stuff before reassembly using what looks like a wallpaper paste brush. Now known to cause pulmonary fibrosis if you breathe the dust for a career, the stuff went out of circulation in tire shops 50 years ago.
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